Light-emitting semiconductor chip

ABSTRACT

A semiconductor chip includes a semiconductor body with a semiconductor layer sequence. An active region intended for generating radiation is arranged between an n-conductive multilayer structure and a p-conductive semiconductor layer. A doping profile is formed in the n-conductive multilayer structure which includes at least one doping peak.

This patent application is a continuation of U.S. patent applicationSer. No. 14/662,037, filed on Mar. 18, 2015 titled “Light-EmittingSemiconductor Chip,” which is a continuation of U.S. patent applicationSer. No. 13/518,809, filed on Aug. 15, 2012, now U.S. Pat. No. 9,012,885and titled “Light-Emitting Semiconductor Chip” which patent applicationis a national phase filing under section 371 of PCT/EP2010/070761, filedDec. 27, 2010, which claims the priority of German patent application 102009 060 747.1, filed Dec. 30, 2009, each of which are incorporatedherein by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a semiconductor chip intended forgenerating radiation.

BACKGROUND

LED semiconductor chips often have an active region intended forgenerating radiation, with a plurality of quantum wells.

SUMMARY OF THE INVENTION

It has become apparent that, when there are InGaN quantum wells in theactive region, the radiant power emitted does not increase in a linearmanner as the current density increases. One cause of this is that thecharge carriers are often not injected efficiently into the quantumwells.

In one aspect, a semiconductor chip is designed so that charge carriersmay be injected efficiently into the active region.

In one embodiment, a semiconductor chip comprises a semiconductor bodywith a semiconductor layer sequence, the semiconductor layer sequencecomprising an n-conductive multilayer structure, a p-conductivesemiconductor layer and an active region intended for generatingradiation. The active region is arranged between the n-conductivemultilayer structure and the p-conductive semiconductor layer. A dopingprofile comprising at least one doping peak is formed in then-conductive multilayer structure.

The doping profile in particular constitutes the profile of the dopingin a vertical direction, thus in a direction which extends in thedirection of deposition of the semiconductor layer sequence of thesemiconductor body. In other words, the doping profile extendsperpendicular to a main plane of extension of the semiconductor layersof the semiconductor layer sequence of the semiconductor body.

For the purposes of the application, a doping peak is understood to meana region of a semiconductor material which has a high dopingconcentration compared with at least one region adjacent thereto. Thesemiconductor material surrounding the doping peak, preferably on bothsides, is preferably low doped, undoped or intrinsic.

A high doping concentration is understood in particular to mean aconcentration of at least 2*10¹⁸ cm⁻³.

A low doping concentration is understood in particular to mean aconcentration of at least 1*10¹⁶ cm⁻³ and at most 1*10¹⁸ cm⁻³.

It has been found that a doping peak which, in particular in comparisonwith the rest of the extent of the n-conductive multilayer structure, isthin and highly doped, leads to improved charge carrier injection intothe active region of the semiconductor chip. As a result of high doping,the n-conductive multilayer structure exhibits comparatively hightransverse conductivity in the region of the doping peak, i.e., highconductivity in the lateral direction, such that charge carriers may beinjected particularly homogeneously into the active region in thelateral direction. The at least one doping peak also results inlaterally more homogeneous current flow in the reverse direction, i.e.,the blocking direction of the active region. In this way, thesemiconductor chips exhibit reduced sensitivity to electrostaticdischarge (ESD).

In a preferred configuration, the n-conductive multilayer structurecomprises at least one region highly doped by means of the doping peakand one region of low n-conductive doping. A doping concentration in theat least one doping peak is preferably at least five times, particularlypreferably at least eight times, for example ten times as high as in theregion of low n-conductive doping of the n-conductive multilayerstructure.

The region of low n-conductive doping may here in particular adjoin thedoping peak.

The doping concentration in the doping peak preferably amounts to atleast 4*10¹⁸ cm⁻³. High conductivity may be achieved as a result of ahigh doping concentration.

Furthermore, the doping concentration in the doping peak preferablyamounts to at most 1*10²⁰ cm⁻³, particularly preferably at most 3*10¹⁹cm⁻³.

Furthermore, the doping concentration in the in particular adjacentregion of low n-conductive doping preferably amounts to at most 5*10¹⁷cm⁻³, particularly preferably at most 2*10¹⁷ cm⁻³.

In one preferred configuration a doping concentration in the at leastone doping peak amounts to at least 4*10¹⁸ cm⁻³ and in the region of lown-conductive doping to at most 8*10¹⁷ cm⁻³.

The vertical extent of the doping peak amounts preferably to between 1nm and 30 nm inclusive, particularly preferably between 2 nm and 20 nminclusive. In particular, the vertical extent of the doping peak mayamount to between 7 nm and 10 nm inclusive.

The n-conductive multilayer structure serves in particular in theinjection of electrons into the active region when the semiconductorchip is in operation. To this end, the n-conductive multilayer structuredoes not necessarily have to be n-conductively doped throughout. Rather,the n-conductive multilayer structure may also comprise one or morelayers in which the n-conductive multilayer structure is undoped orintrinsic.

Accordingly, the p-conductive semiconductor layer is intended inparticular for the injection of holes into the active region. Thep-conductive semiconductor layer may also be of multilayer construction,wherein individual layers may differ with regard to doping and/orcrystal composition.

The semiconductor body is preferably based on a compound semiconductor,in particular on a nitride compound semiconductor.

“Based on nitride compound semiconductors” means in the present contextthat the active epitaxial layer sequence or at least one layer thereofcomprises a III/V nitride compound semiconductor material, preferablyAl_(y)Ga_(1-x-y)In_(x)N, wherein 0≦x≦1, 0≦y≦1 and x+y≦1. This materialdoes not absolutely have to exhibit a mathematically exact compositionaccording to the above formula. Instead, it may comprise one or moredopants and additional constituents which do not substantially modifythe characteristic physical properties of the Al_(y)Ga_(1-x-y) In_(x)Nmaterial. For simplicity's sake, however, the above formula includesonly the fundamental constituents of the crystal lattice (Al, Ga, In,N), even if these may in part be replaced by small quantities of furthersubstances.

The active region preferably comprises a plurality of quantum layers.The quantum layers are conveniently arranged between barrier layers. Thequantum layers and barrier layers may here form a quantum structure.

For the purposes of the application, the term “quantum structure”includes in particular any structure in which charge carriers mayundergo quantisation of their energy states by inclusion(“confinement”). In particular, the term quantum structure does notprovide any indication of the dimensionality of the quantisation. Itthus encompasses inter alia quantum wells, quantum wires and quantumdots and any combination of these structures.

In a preferred configuration, the n-conductive multilayer structurecomprises a quantum structure. This quantum structure may comprise aplurality of quantum layers.

The term quantum structure is furthermore understood to mean inparticular both a configuration as a multi quantum well structure (MQW)and a configuration as a superlattice. Unlike in a multi quantum wellstructure, in a superlattice the distances between adjacent quantumlayers are so small that electron states of adjacent quantum layerscouple together quantum mechanically and form common electron states.

Barrier layers may for example be provided between the quantum layers ofa superlattice, which barrier layers have a thickness of 5 nm or less,for example 2 nm.

In a preferred configuration, a band gap of the quantum layer of then-conductive multilayer structure is at least as large as a band gap ofthe quantum layer of the active region. Particularly preferably, theband gap of the quantum layer is larger than the band gap of the quantumlayer of the active region. For example, in the case of a semiconductorchip based on a nitride compound semiconductor material, the quantumlayers of the n-conductive multilayer structure may have a lower indiumcontent x than the quantum layers of the active region.

Unlike the quantum layers of the active region, the quantum layers ofthe n-conductive multilayer structure are not intended for generatingradiation, but rather serve in particular for efficient injection ofelectrons into the active region, in which they may recombine with holeswith the emission of radiation.

The quantum layers of the active region are preferably intrinsic orundoped.

In a further preferred configuration, the doping peak is arrangedbetween the quantum layer of the n-conductive multilayer structureclosest to the active region and the quantum layer of the active regionclosest to the n-conductive multilayer structure. Good lateral currentdistribution in the vicinity of the active region is thus ensured.

Furthermore, the distance of the doping peak from the active region, inparticular from the quantum layer of the active region closest to then-conductive multilayer structure, amounts to a distance of between 1 nmand 30 nm inclusive, particularly preferably between 2 nm and 20 nminclusive, in particular between 7 nm and 10 nm inclusive.

By means of this highly doped doping peak in the vicinity of the activeregion, injection of charge carriers into the active region may takeplace particularly efficiently and in particular particularlyhomogeneously in the lateral direction. The at least one doping peakalso brings about improved utilisation of a large number of possiblecharge carrier paths due to the high transverse conductivity, whichreduces the risk of ESD damage compared to a semiconductor chip with nodoping peaks in the n-conductive region of the semiconductor body.

The at least one doping peak is preferably configured such that thedoping profile comprises sharp transitions from a low dopingconcentration to a high doping concentration and vice versa. Onproduction of the semiconductor chip, this may be achieved by a lowgrowth rate, for instance a rate of between 20 nm/h and 500 nm/h.Deposition preferably proceeds epitaxially, for instance by means ofMOCVD.

In a preferred further development a crystal structure of then-conductive multilayer structure comprises V-shaped indentations. Suchindentations, which may form during deposition of the semiconductorlayers in particular along dislocation lines, are also known as “Vpits.” Such V-shaped indentations may form in particular at acomparatively low deposition temperature of the semiconductor material,for instance below 950° C. These V-shaped indentations may lead toimproved behaviour of the semiconductor chip in the non-conductingdirection.

In a further preferred configuration, the doping profile may comprise atleast one further doping peak. In particular, at least one quantum layerof the n-conductive multilayer structure may be arranged between thedoping peak and the further doping peak. In other words, the dopingprofile may be configured such that one part of the quantum layers ofthe n-conductive multilayer structure is highly n-doped, while theremaining part of the quantum layers is low n-doped compared thereto.

The doping profile may also comprise more than two doping peaks, inparticular between one and five doping peaks inclusive, preferablybetween one and three doping peaks inclusive.

In a preferred configuration of the semiconductor chip, a growthsubstrate for the semiconductor layer sequence of the semiconductor bodyis removed completely or at least partially. Such a semiconductor chipis also known as a thin film semiconductor chip.

A thin-film semiconductor chip, for instance a thin-film light-emittingdiode chip, may furthermore be distinguished for the purposes of thepresent invention by at least one of the following characteristicfeatures: on a first major surface, facing a carrier element, of asemiconductor body comprising a semiconductor layer sequence with anactive region, in particular of an epitaxial layer sequence, a mirrorlayer is applied or formed, for instance integrated as a Bragg mirror inthe semiconductor layer, said mirror layer reflecting back into thesemiconductor layer sequence at least some of the radiation generated insaid sequence; the semiconductor layer sequence has a thickness in therange of 20 μm or less, in particular in the range of 10 μm; and/or thesemiconductor layer sequence contains at least one semiconductor layerwith at least one face which comprises an intermixing structure, whichideally leads to an approximately ergodic distribution of the light inthe semiconductor layer sequence, i.e., it exhibits scattering behaviourwhich is as ergodically stochastic as possible.

The basic principle of a thin-film light-emitting diode chip isdescribed for example in I. Schnitzer et al., Appl. Phys. Lett. 63 (16),18 Oct. 1993, 2174-2176, whose disclosure content is hereby included byreference in this respect in the present application.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features, configurations and convenient aspects are revealed bythe following description of the exemplary embodiments in conjunctionwith the figures, in which:

FIG. 1A is a schematic sectional view of an exemplary embodiment of asemiconductor body with a semiconductor layer sequence,

FIG. 1B shows schematic representations of a conduction band edgeprofile E_(C) and a doping profile in each case in a depositiondirection z for a portion of a semiconductor body according to a secondexemplary embodiment,

FIG. 2 is a schematic sectional view of a first exemplary embodiment ofa semiconductor chip,

FIG. 3 is a schematic sectional view of a second exemplary embodiment ofa semiconductor chip, and

FIG. 4 shows the result of measurement of a current I as a function of avoltage U applied in the reverse direction.

Identical, similar or identically acting elements are provided withidentical reference numerals in the figures.

The figures are in each case schematic representations and are thereforenot necessarily true to scale. Rather, comparatively small elements andin particular layer thicknesses may be illustrated on an exaggeratedlylarge scale for clarification.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

A first exemplary embodiment of a semiconductor body for a semiconductorchip is illustrated schematically in sectional view in FIG. 1A. Thesemiconductor body 2 comprises a semiconductor layer sequence whichforms the semiconductor body. The semiconductor layer sequence comprisesan active region 20 intended for generating radiation, which is arrangedbetween an n-conductive multilayer structure 21 and a p-conductivesemiconductor layer 22. The semiconductor layer sequence of thesemiconductor body is preferably deposited epitaxially, in particular byMBE or MOCVD, on a growth substrate 29. Examples of materials suitableas a growth substrate for a semiconductor body based on a nitridecompound semiconductor material are sapphire, silicon carbide, siliconor gallium nitride. A buffer layer may be formed between then-conductive multilayer structure 21 and the growth substrate, whichbuffer layer may in particular be provided to enhance crystal quality(not shown explicitly).

The active region 20 comprises a quantum structure which is formed by aplurality of quantum layers 201 and a plurality of barrier layers 202arranged between the quantum layers. The active region here comprises,merely by way of example, a quantum structure with three quantum layers.In contrast thereto, however, another number of quantum layers, forexample just one or two quantum layers or more than three, for instanceup to 20 quantum layers, for example five to eight quantum layers, mayalso be provided.

The p-conductive semiconductor layer 22 may also be of multilayerconfiguration, wherein the individual layers may differ from one anotherin particular by the material composition and/or by the doping thereof.

The n-conductive multilayer structure 21 comprises a quantum structurewith a plurality of quantum layers 211, which are arranged betweenbarrier layers 212.

A position of a doping peak 4 in the vertical direction, i.e., in adirection perpendicular to a main plane of extension of thesemiconductor layers of the semiconductor body 2, is shown schematicallyby means of an arrow. The doping peak is located in the n-conductivemultilayer structure 21, in particular between the quantum layer 211 ofthe n-conductive multilayer structure closest to the active region andthe quantum layer 201 of the active region 20 closest to then-conductive multilayer structure. In a region of the n-conductivemultilayer structure adjoining the doping peak 4, the quantum layers 211and the barrier layers adjoining the quantum layers are low doped.

Efficient injection of electrons into the active region 20 may proceedby means of the doping peak 4. In the reverse direction, the doping peaklikewise brings about improved current spreading, which leads to areduced risk of ESD damage to the semiconductor chip formed by means ofthe semiconductor layer sequence. Reduced ESD sensitivity is thusachieved as early as with deposition of the semiconductor layersequence, so reducing the risk of damage to the semiconductor chip in asubsequent production step.

A schematic profile of a conduction band edge profile E_(C) and of asilicon doping profile is shown in FIG. 1B as a function in the zdirection for a second exemplary embodiment of a semiconductor body fora semiconductor chip. The z direction corresponds to the direction ofdeposition of the semiconductor layers of the semiconductor body 2 andextends perpendicular to a main plane of extension of the semiconductorlayers of the semiconductor body 2.

This second exemplary embodiment corresponds substantially to the firstexemplary embodiment, described in conjunction with FIG. 1A, of asemiconductor body. In contrast thereto, a further doping peak 41 isprovided in this exemplary embodiment.

The further doping peak 41 forms a highly doped sub-region of thequantum structure of the n-conductive multilayer structure 21. Betweenthe further doping peaks and the doping peak 4 there is provided aregion of low n-conductive doping 45 of the quantum structure.

The semiconductor body 2, in particular the active region 20, is basedin this exemplary embodiment on a nitride compound semiconductormaterial.

The active region 20 comprises a plurality of quantum layers 201. Inthis exemplary embodiment the active region is intended for generatingradiation in the blue spectral range. To this end, the quantum layerseach comprise an indium content of x=0.2. The active region may howeveralso be configured to emit radiation in a different spectral range. Thehigher the indium content, the lower the band gap and thus the energy ofthe photons generatable in the active region. The indium content maythus be varied within broad limits. For example, quantum layers with anindium content of x=0.10 emit radiation when in operation in theultraviolet spectral range and quantum layers with an indium content ofx=0.40 emit radiation in the green spectral range. Between the quantumlayers GaN barrier layers 202 are arranged.

The doping profile for the n-conductive multilayer structure 21 isproduced in this exemplary embodiment by means of silicon doping. Adifferent dopant may also be used, however.

The doping profile comprises a doping peak 4. This doping peak amountsin this exemplary embodiment to a width of approximately 5 nm. In theregion of the doping peak 4 the doping concentration amounts to 1*10¹⁹cm⁻³, while the doping concentration in a region of low n-conductivedoping 45 adjoining the doping peak 4 comprises a doping concentrationof 1*10¹⁷ cm⁻³. Furthermore, the doping profile comprises a furtherdoping peak 41 with a width of 15 nm, in which the n-conductivemultilayer structure is n-conductively doped with a doping concentrationof 1*10¹⁹ cm⁻³.

By means of the doping peaks, charge carrier injection which isparticularly uniform in the lateral direction may be achieved. Efficientcurrent spreading therefore takes place, in particular immediately belowthe quantum layers 201 of the active region.

The n-conductive multilayer structure 21 comprises, as described inconnection with FIG. 1A, a quantum structure with a plurality of quantumlayers 211, which are arranged in each case between barrier layers 212.The doping profile results in a low doped sub-region 215 of the quantumstructure and a highly doped sub-region 216 of the quantum structure. Inthese regions, the quantum layers and/or the barrier layers may each bedoped. Preferably, the quantum layers and the barrier layers are highlydoped, at least in the region of the at least one doping peak.

The n-conductive multilayer structure 21 thus comprises both a low dopedsub-region of the quantum structure and a highly doped sub-region of thequantum structure. The low doped sub-region 215 of the quantum layershere extends between the doping peaks 4, 41 and forms an electronreservoir when the semiconductor chip is in operation. In the low dopedsub-region of the quantum structure, the quantum layers 211 and thebarrier layers 212 are low doped. The doping peak 4 brings aboutparticularly efficient and laterally homogeneous injection of chargecarriers from the n-conductive multilayer structure 21 into the quantumlayers of the active region 20.

In this exemplary embodiment the quantum layers of the n-conductivemultilayer structure 21 comprise an indium content of x=0.1, by way ofexample. The indium content may however also be selected to be differenttherefrom. The indium-content is preferably at most as high as theindium content of the quantum layers in the active region, such that theband gap of the quantum layers of the n-conductive multilayer structure21 is larger than the band gap of the quantum layers in the activeregion 20 or corresponds to the band gap of the quantum layers in theactive region.

The quantum structure of the n-conductive multilayer structure may inparticular take the form of a quantum well structure or a superlattice,for example with barrier layers of a thickness of less than 5 nm, forinstance of approximately 2 nm.

Efficient injection of charge carriers into the active region issimplified thereby.

It goes without saying that the material compositions of the activeregion 20 and the n-conductive multilayer structure 21 and the dopingprofile may also deviate from the exemplary embodiment illustrated.

Preferably, a doping concentration in at least one doping peak 4 amountsto at least 4*10¹⁸ cm⁻³. Furthermore, the doping concentration in thedoping peak preferably amounts to at most 1*10²⁰ cm⁻³, particularlypreferably at most 3*10¹⁹ cm⁻³.

In the region of low n-conductive doping 45 the doping concentrationpreferably amounts to at most 5*10¹⁷ cm⁻³, particularly preferably atmost 2*10¹⁷ cm⁻³.

The doping concentration in the at least one doping peak is preferablyat least five times, particularly preferably at least eight times ashigh as in the region of low n-conductive doping of the n-conductivemultilayer structure.

The thickness, i.e., vertical extent, of the doping peak 4 and/or thefurther doping peak 41 preferably amounts to between 1 nm and 30 nminclusive, particularly preferably between 2 nm and 20 nm inclusive,most preferably between 7 nm and 10 nm inclusive.

The doping peak 4 is preferably at a small distance from the activeregion 20, particularly preferably at a distance of at most 30 nm, inparticular between 1 nm and 30 nm inclusive, preferably between 2 nm and20 nm inclusive, most preferably between 7 nm and 10 nm inclusive.

Furthermore, unlike in the exemplary embodiments shown, more than twodoping peaks may also be provided, for example between one and fivedoping peaks inclusive.

In addition, unlike in the exemplary embodiments shown then-conductively doped multilayer structure 21 may also comprise layers orsublayers which are undoped or intrinsic. In this case, the undoped orintrinsic layers are conveniently thin enough for the n-conductivemultilayer structure 21 to exhibit sufficiently high conductivity forelectrons in the deposition direction.

To produce an as far as possible rectangular profile for the dopingprofile in the region of the doping peaks 4, 41 deposition preferablyproceeds with a low growth rate, for example with a rate of between 20nm/h and 500 nm/h inclusive.

Furthermore, the crystal structure of the n-conductive multilayerstructure preferably comprises V-shaped indentations, which form inparticular at low deposition temperatures, for instance below 950° C.,in increased numbers along dislocations. These V-shaped indentations maylead to improved behaviour of the semiconductor chip on application of avoltage in the non-conducting direction.

A first exemplary embodiment of a semiconductor chip 1 is shown in FIG.2, the semiconductor body 2 being constructed by way of example asdescribed in relation to FIG. 1A.

The semiconductor chip 1 here takes the form of a thin film LEDsemiconductor chip, in which the growth substrate 29 (FIG. 1A) for thesemiconductor layer sequence of the semiconductor body 2 has beenremoved. The active region 20 is provided to generate incoherentradiation when in operation.

The semiconductor body 2 is arranged on a carrier 5. The carrier 5serves in particular in mechanical stabilisation of the semiconductorbody, such that the growth substrate is not needed for this purpose.

A semiconductor material, for example silicon, gallium arsenide orgermanium, or a ceramic, for instance aluminium nitride, is suitable ascarrier material.

The carrier 5 is connected mechanically stably and also electricallyconductively to the semiconductor body by means of a bonding layer 8.

A suitable bonding layer is, for example, a solder or an electricallyconductive adhesive.

A mirror layer 62 is formed between the carrier 5 and the semiconductorbody 2. By means of the mirror layer, radiation generated in the activeregion 20 when the semiconductor body 2 is in operation, which isemitted in the direction of the carrier 5, may be reflected in thedirection of the radiation exit face 200 and thus leave thesemiconductor chip.

On the side of the semiconductor body 2 remote from the carrier 5, thesemiconductor body comprises a first contact 31. On the opposing side ofthe semiconductor chip, i.e., on the side of the carrier 5 remote fromthe semiconductor body 2, a second contact 32 is formed.

The first contact and/or the second contact preferably contain a metal,for example gold, silver, platinum, aluminium, nickel, chromium orcopper or an alloy with at least one of the stated materials.

By means of the first contact 31 and the second contact 32, chargecarriers may be injected into the active region 20 from different sideswhen the semiconductor chip 1 is in operation and there recombine withemission of radiation.

The electrons injected via the first contact 31 are efficientlydistributed in the lateral direction in the n-conductive multilayerstructure 21 in the region of the at least one doping peak 4 and coupledin uniformly into the quantum layers 201 of the active region 20.

The mirror layer 62 is preferably of metallic construction and moreoverpreferably exhibits high reflectivity for the radiation generated in theactive region. Examples of suitable materials for the mirror layer are ametal, for instance aluminium, silver, gold, palladium or rhodium or ametal alloy with at least one of the stated metals.

A second exemplary embodiment of a semiconductor chip 1 is illustratedschematically in sectional view in FIG. 3. The semiconductor body 2 ishere again constructed as described in relation to FIG. 1A. Unlike thesemiconductor chip according to the first exemplary embodiment describedin relation to FIG. 2, the semiconductor body 2 comprises a recess 24,which extends from a side facing the carrier 5 through the p-conductivesemiconductor layer 22 and through the active region 20 into then-conductive multilayer structure 21. The recess here passes through thequantum layers 211 of the n-conductive multilayer structure. The sidefaces of the recess are covered by an insulation layer 27, whichprotects the semiconductor body 2 from an electrical short circuit ofthe active region 20.

A contact layer 65 is formed in the recess 24, which layer serves inelectrical contacting of the active region from the side remote from thep-conductive semiconductor layer 22.

The carrier 5 comprises a first land 51 and a second land 52, whereinthe first land 51 is connected electrically conductively via the contactlayer 65 to the n-conductive multilayer structure 21 and the second land52 is connected electrically conductively via the mirror layer 62 to thep-conductive semiconductor layer 22. The first land 51 and the secondland 52 are arranged on the same side of the carrier 5.

By means of the recess 24, the n-conductive multilayer structure 21arranged on the side of the active region 20 remote from the carrier 5is electrically contactable, such that the radiation exit face 200 maybe free of an external electrical contact. Shading of the radiation exitface by a contact which is not radiation-transmissive is therebyprevented.

The carrier 5 comprises openings 55 which extend from a first major face501 of the carrier facing the semiconductor body 2 through to a secondmajor face 502 opposite the first major face. By means of theseopenings, the first land 51 is connected electrically conductively tothe first contact 31 and the second land 52 is connected electricallyconductively to the second contact 32, such that the semiconductor chip1 is externally electrically contactable from the bottom of thesemiconductor chip remote from the radiation exit face 200.

Furthermore, the semiconductor body 2 comprises patterning 7 on the sideof the radiation exit face 200. The patterning serves to reduce totalreflection of radiation generated in the active region within thesemiconductor chip and thus to increase outcoupling efficiency. It goeswithout saying that such patterning may also be provided in the firstexemplary embodiment of the semiconductor chip described in relation toFIG. 2.

FIG. 4 shows the behaviour of the reverse current I as a function of thevoltage in the reverse direction, i.e., in the non-conducting directionof the active region 20. A curve 99 here shows measurements at asemiconductor layer sequence from which the semiconductor bodies for thesemiconductor chips are obtained with subsequent processing. Thesemiconductor layer sequence is here constructed as described inrelation to FIG. 1B.

In comparison, a curve 98 shows measurements at a semiconductor layersequence in which a conventional n-conductive region without dopingpeaks is used.

An arrow 97 illustrates how the above-described structure of then-conductive multilayer structure 21 makes it possible for the currentprofile to increase more slowly initially for small voltages and only toincrease steeply with very high voltage values. The measurement curvethus shows a considerably more pronounced, bend-like profile.

The description of an LED semiconductor chip is used merely by way ofexample to describe the exemplary embodiments. The above-describedconfiguration of the n-conductive multilayer structure 21 and of thedoping profile with at least one doping peak 4 may however also be usedfor a component emitting coherent or at least partially coherentradiation, for example for a surface-emitting or an edge-emittingsemiconductor laser chip or for an RCLED (resonance cavity lightemitting diode).

The invention is not restricted by the description given with referenceto the exemplary embodiments. Rather, the invention encompasses anynovel feature and any combination of features, including in particularany combination of features in the claims, even if this feature or thiscombination is not itself explicitly indicated in the claims or theexemplary embodiments.

The invention claimed is:
 1. A semiconductor chip comprising: asemiconductor body with a semiconductor layer sequence, thesemiconductor layer sequence comprising an n-conductive multilayerstructure, a p-conductive semiconductor layer, and an active regionprovided for generating radiation; and a contact layer; wherein then-conductive multilayer structure has a doping profile comprising atleast one doping peak; wherein the semiconductor body has a recess thatextends through the p-conductive semiconductor layer and the activeregion into the n-conductive multilayer structure; wherein the recesspenetrates the at least one doping peak; and wherein the contact layeris disposed in the recess and electrically contacts the n-conductivemultilayer structure.
 2. The semiconductor chip according to claim 1,wherein a doping concentration in the at least one doping peak is atleast five times as high as a doping concentration in a region of lown-conductive doping of the n-conductive multilayer structure.
 3. Thesemiconductor chip according to claim 2, wherein the dopingconcentration in the at least one doping peak is at least 4*10¹⁸ cm⁻³and wherein the doping concentration in the region of low n-conductivedoping is at most 8*10¹⁷ cm⁻³.
 4. The semiconductor chip according toclaim 1, wherein the at least one doping peak has a vertical extent thatis between 1 nm and 30 nm, inclusive.
 5. The semiconductor chipaccording to claim 4, wherein the at least one doping peak has avertical extent that is between 5 nm and 20 nm, inclusive.
 6. Thesemiconductor chip according to claim 1, wherein the at least one dopingpeak has a distance from the active region that is between 2 nm and 20nm, inclusive.
 7. The semiconductor chip according to claim 1, whereinthe n-conductive multilayer structure comprises a quantum structure witha first plurality of quantum layers.
 8. The semiconductor chip accordingto claim 7, wherein the active region comprises a second plurality ofquantum layers, wherein the at least doping peak is arranged between afirst quantum layer of the first plurality of quantum layers of then-conductive multilayer structure that is closest to the active regionand a second quantum layer of the second plurality of quantum layers ofthe active region that is closest to the n-conductive multilayerstructure.
 9. The semiconductor chip according to claim 8, wherein aband gap of at least one quantum layer of the first plurality of quantumlayers of the n-conductive multilayer structure is at least as large asa band gap of at least one quantum layer of the second plurality ofquantum layers of the active region.
 10. The semiconductor chipaccording to claim 7, wherein the doping profile comprises a firstdoping peak and a second doping peak, wherein at least one quantum layerof the first plurality of quantum layers of the n-conductive multilayerstructure is arranged between the first doping peak and the seconddoping peak.
 11. The semiconductor chip according to claim 10, wherein asub-region of the quantum structure of the n-conductive multilayerstructure comprises a high doping concentration by way of the seconddoping peak.
 12. The semiconductor chip according to claim 1, whereinthe n-conductive multilayer structure comprises a plurality of quantumlayers; and wherein the recess penetrates the plurality of quantumlayers of the n-conductive multilayer structure.
 13. The semiconductorchip according to claim 1, wherein the active region is based on anitride compound semiconductor material.
 14. The semiconductor chipaccording to claim 1, wherein a crystal structure of the n-conductivemultilayer structure comprises V-shaped indentations.
 15. Thesemiconductor chip according to claim 1, wherein a growth substrate forthe semiconductor layer sequence is removed from the semiconductor body.16. A semiconductor chip comprising: a semiconductor body with asemiconductor layer sequence, the semiconductor layer sequencecomprising an n-conductive multilayer structure; and a contact layer;wherein the n-conductive multilayer structure has a doping profilecomprising at least one doping peak; wherein the semiconductor body hasa recess that penetrates the doping peak; and wherein the contact layerin the recess electrically contacts the n-conductive multilayerstructure.
 17. The semiconductor chip according to claim 16, wherein thesemiconductor layer sequence further comprises a p-conductivesemiconductor layer and an active region provided for generatingradiation, the recess extending through the p-conductive semiconductorlayer and the active region.
 18. A semiconductor chip comprising: asemiconductor body with a semiconductor layer sequence, thesemiconductor layer sequence comprising an n-conductive multilayerstructure and an active region provided for generating radiation; acarrier, the semiconductor body being arranged on the carrier; and acontact layer; wherein the n-conductive multilayer structure has adoping profile comprising at least one doping peak; wherein then-conductive multilayer structure is arranged on a side of the activeregion remote from the carrier; wherein the semiconductor body has arecess that penetrates the doping peak; and wherein the contact layer isarranged in regions between the carrier and the semiconductor body andelectrically contacts the n-conductive multilayer structure.